BANGKOK, Thailand -- Advancing Thai floodwaters breached barriers protecting Bangkok's second-largest airport yesterday, halting commercial flights, as the prime minister warned that the capital could be swamped by up to 5 feet of water if flood walls fail.

The flooding at Don Muang airport, which is primarily used for domestic flights, is one of the biggest blows yet to government efforts to prevent the sprawling capital from being inundated. Its effective closure is certain to further erode public confidence in the ability of Prime Minister Yingluck Shinawatra's administration to defend the increasingly anxious metropolis of 9 million people.

Bangkok's Suvarnabhumi Airport, the country's main international gateway, has yet to be affected by flooding, and flights there were operating normally. Most of the city has been spared inundation so far.

Yingluck's government declared a five-day public holiday yesterday in affected areas, including Bangkok, while the Education Ministry ordered schools to close until Nov. 7.

The prime minister warned in a televised address that in a worst-case scenario, the enormous pressure of floodwaters pushing downstream into the city could combine with monthly high tides Friday and Saturday to overwhelm recently reinforced flood walls and embankments protecting the city.

Bangkok Gov. Suhumbhand Paribatra said the capital cannot escape flooding and warned residents of 13 districts along the Chao Phraya river, the city's biggest waterway, to be prepared.

The flooding yesterday at Don Muang airport symbolizes the gravity of the Southeast Asian nation's deepening crisis, which has seen advancing waters submerge much of the country and kill 366 people in the last three months.

The airport has been converted into an overcrowded shelter filled with tents for about 4,000 people who fled waterlogged homes.

Somboon Klinchanhom, 43, took refuge there last week but was preparing to move after authorities said the terminal had become too crowded and thousands of people displaced there would be relocated.

"I thought it would be safe and well-protected," Somboon said of the airport.

Latest videos